Unfunny

Engine 2021: knock knock?

Me: Who's there?

Engine 2021: Your connecting rods!

Me: %@#*! $#!^!!!!!

Some car jokes are funny. Automotive "knock knock" jokes are not... But if you're gonna race a heavily modified car it's a risk. Unfortunately, in this case I was caught between the intersection of Road Racing and Autocross... 

The engine had been newly built in 2020 to support 9250 rpm redline and use 14:1 compression, this had involved special valves, Ferrea roller rockers, lightened crank, Carillo rods, Cosworth pistons, and an externally driven oil pump system. This system was a half step between the traditional wet sump and a dry sump system. Basically it ran a pump off the crank that sucked oil out of the back of the pan which had had the drain plug replaced with an AN fitting. 

The engine was delivered in the spring of 2020... when covid was at its worst. During this period I was not very motivated because no racing was being held for the foreseeable future, and even when the first events were opening up I didn't want to attend because I and my wife have contact with vulnerable individuals. So, once things seemed to be turning around I got motivated again, but I had to go slow and be careful because the car had been apart so long. In the end I managed to get the car running again for 2 events at the end of the 2020 season. Both events turned out to be extremely tight, low speed courses. One so much so that my co-driver decided the course just wasn't fun and didn't bother with the last run.

These events showed that re-assembly went well and there were no major issues on that front, but also failed to really stress the car. It's possible that speeds on these two courses never exceeded 55mph. So when I put the car away at the end of 2020 it seemed like all was well. Unfortunately this was not true. 

The oiling solution had been supplied by Dynamic Racing Solutions who built the engine, and they claim they had used it successfully on two track cars. They are stand up folks who have a solid reputation on Lotus Talk forums, and field mid pack or better cars for professional TC Series races, so I don't doubt that this is true. But as road racers are often amusingly keen to point out autocross is not road racing. 

Road racing has hard stops no doubt, and they pull plenty of sideways G's too... but the transitions between those actions are smoother and less violent most of the time. Also road racers rarely hit the rev limiter or shift as soon as they do. Autocrossers do so regularly, and may ride the limiter, because we just don't have time to be shifting up and then back down unless there's a LOT of rev limiter. For anything less than about 1.5-2 seconds of rev limiter shifting is slower for autocross.

First event 2021 had a much more typical course. It was clockwise and the run through the small runway was mostly the type of sweeping transitions my car excels at. Because of my massive tires and big wing/splitter, after the initial slalom I found I was able to just keep the pedal down, and I touched the rev limiter just before the braking zone. I stabbed the brakes bled just enough speed and had an absolutely fabulous run through the sweeper onto the main run way, exiting hard on the gas. THIS was what I had built the car for and it took off like a rocket and quickly found the rev limiter again, this time for something close to the 2 seconds that would suggest maybe shifting is profitable. I managed appropriate braking for entering the slalom after the faster section...

Up until this point I was in Nirvana. Somehow I had more or less nailed the course so far on my first run and everything felt just GREAT. I can still remember that joy. It was that good. 

I entered the slalom with maybe just a tiny bit too much speed for the hard back side entry, but still basically it went well, and soon I went to add more speed... But then, the bottom fell out of my world. The car lagged and slowed rather than accelerated. I was momentarily confused. It felt like fuel starve, I wondered if I'd forgotten fuel. But soon it was clear something was wrong. 

I limped back to grid with the car actually threatening to stall on me at one point but then seeming to smooth out a bit about the time I got to the finish... I coasted back gently and talked it over with my co-driver. I decided to take it back to the trailer, hook up the computer and see what I could see. As I pulled out of my grid slot I heard a "clack clack clack" sound that I had never heard before. I quickly found it to be repeatable any time I pushed the engine to 2krpm, I quickly realized that it could pretty much only be one thing. I coasted up to the trailer ramp and shut it off. Friends helped me push it onto the trailer. 

My new engine had rod knock.

Data from the ECU showed that the clanking of the rods triggered the engine knock protection, and this very likely prevented me from throwing a rod through the side of the block entirely. If such a thing had happened on the exhaust side of the block, fire and total loss would have been possible. Hooray for good knock sensors and sensible ECU protection routines provided by Cohesion Motorsports!

The combination of working fine in slow courses, and failing bearings after hard brake / turn / accel / limiter pointed straight at the oiling system. Removing the pan I found that though 3/4 of the baffling had been retained there were some gaps where the 4th side had been removed probably allowing some oil to escape along the sides. Then I went back and watched one of my earlier videos and right at the end after the stop into the finish I heard a now way too familiar sound... 

Just a brief second of rod knock sound there and at low speed, probably nearly harmless as such aside from some minor wear acceleration, but a harbinger of the disaster to come. Not having heard it before I didn't recognize it in 2020. 

As described above, I would have broke hard and then accelerated to 9250 rpm immediately, so that knock would have arrived just as I got to around 8-9krpm... no good. A track car would have been turning, but usually waiting slightly before feeding in the power exiting a turn. Plus the track car would have had a shift point in there to bring the revs back down. What we call a sweeper in Autocross is a crazy sharp hairpin on a track. The oil would have sloshed forward, and then immediately leftwards with the motor working hard/fast to redline without oil and without pause.

My brand new race engine that only lasted for about 20 minutes... not funny at all.

Cone Dodgy Numbers

This post is not to be taken seriously. No seriously, I mean that. This post is where I attempt to guesstimate the results of my latest power improvements, and I will be venturing into the world of comparing results from different dynamometers and no such comparison should ever be trusted, but all too often it's the best we can do, so let me make some excuses, and then we can get on with the dubious number wrangling.

Click here to skip my rambling and just see the graph....

Theory

In theory the right way to upgrade a car's power is to do a several dyno pulls on dyno A before modification and then after modification calibrate and re-measure on the same dyno A. For further modifications, one would ideally have another before/after pull on Dyno A. Dyno B which is a different dyno altogether shan't be involved and dyno C is right out! 

Excuses

I didn't do that. Not because it's a bad idea but due to a combination of time constraints, weather and cost. After all, dyno time is not free.

• Weather: Modifications of major magnitude are often done in the winter, and the decision to proceed often coincides with the onset of cold weather. Once the snow is up, toting around the 20ft trailer becomes a lot less fun. The risk of loosing everything I worked on due to one ice patch or similar is daunting because I'm not maid out of money. 
• Time: If I would decide earlier in the season this would be less of a problem, but when engines, or major portions thereof are being replaced and the first event is early April, and one pulls the trigger after Christmas, adding a trip to the dyno into the schedule is dubious, especially since the engine builder wanted some key parts off the original to get started.
• Cost, well dyno time isn't free, but the time off to visit a dyno is potentially even more expensive, and as I said, I'm not made of money.

Ok them's my excuses and that's that. (Well yes it does boil down to Gus is cheap and he procrastinates... shhh!) 

Also in this case there was a necessary switch in dynos because the dyno from last time was down for service, so even though I stuck with my Emtron ECU and my tuner Nick, I had to take it to a different location. 

Funny Math

Even using the same machine, day to day atmospheric difference can cause some variation, but as a rule aside from what the operator might do inputing measured temps/humidity/pressure there's little one can do to ensure equality there so one just hopes that that source of error is not significant. 

Beyond that the different brand of dyno have different overall reading tendencies, much of which is fuzzy despite no end of internet discussions on the topic. Obviously, in the real world a given pull releases X amount of heat energy, and Y % of that winds up being used to accelerate the dynamometer. In theory they should all get the same result but in practice they don't, and the proprietary nature of their software and hardware is such that it's bad business for any Manufacturer to clarify how their numbers relate to this theoretical truth. All that any consumer grade dyno actually guarantees is consistency for runs on that dyno (assuming consistent atmospheric conditions of course). For tuning an engine that's what's really required, and so no shop is going to invest in a system calibrated to a real world standard. Only large OEM's have that kind of budget, and they "simplify" things by measuring the engine outside of the car anyway. ("Brake" horse power).

So in the portion of the world not working with multi-million dollar test labs, we have to wing it. 

The dynos in question are a Dynojet (last build) and a Dyno Dynamics (this build). What we do know from the internet, and from the claims of my tuner is that Dyno Dynamics is among the "heat breaker" dynos. The readings from these dynos tend to be lower than the much more common and nearly industry standard Dynojets. Both the Nick and the world wide web say something like 10-15% lower readings for the same car on a DynoDynamics vs a Dynojet, but that's a really really huge range. For a 190hp reading that's a range of 209 to 219, and for a build that is comming off of a 193 Dynojet reading that's a 60% difference in how much power was added, and saying a range always leads the conversation into hemming and hawing in an unsatisfying way, so I want to pick a number and have some basis for it that is is only partly insane.

Rather than using an internet post with little or no known basis in fact, I'm going to lean on my knowledge of what changes are being made to the car and derive a "possible" factor to convert the new dyno readings to the scale for the old dyno. 

Some Logic?

Things I know about the effects of the changes to the car that are relevant to this exercise include:

1. The Compression ratio changed from 11.5:1 to 14.0:1, and according to this page, that's supposed to give a 5.7% increase in power. This is based in hard physics including the Ideal Gas Law (PV=nRT) etc. so, unless something else changes, it should be fairly predictable.
2. The RPM limit is being raised to 9200, this means peak HP is not comparable and we can't use that number for scaling things, we should be using peak torque instead.
3. The new roller-rocker setup deletes the variable lift function and ignores the lower cam. The lower cam is so named because it functions in the lower RPM's, typically below 6200. Any measurement below the cam switch point in the old build has both cam and compression changes to account for, so it's hard to predict the change under 6200 rpm.
4. The cold air intake was increased from 2.75" to 3" and the throttle body from 65mm to 70mm, so the upper RPMs are likely benefiting from that change as well as the compression change 

So it sounds like there's nothing left, but that's not quite true. I *think* its reasonable to presume that the air intake is never limiting the developed torque until after the torque peak. Other factors could limit it first, but with the torque increasing, the air is not limiting, and thus below the torque peak and above the cam switch in the old tune is an area that  should be valid for comparison where only the compression change should be having an effect. Conveniently torque peaks are also frequently reported on dyno sheets. That conclusion of course relies on the assumption that the port/polish jobs and valve flow are similar, but I have no reason to suspect changes there. 

One thing I'm leaving out is the effect of the lighter pistons, and the lighter crank, which probably provide a slight gain beyond the 5.7% because less energy is stored as kinetic energy in the rotating assembly, but I would also expect the belt driven external oil pump to have a little more drag than the O.E.M. internal pump, so I'm going to guess that those are both small and mostly offsetting each other.

So that seems to imply that I can have a solid expectation based on a very inflexible bit of physics for the change at the old build's torque peak. The old torque peak was 142.1 ft/lbs at 6750 RPM (luckily this is solidly above the cam switch) and the expected result is 150.2 flt/bs at 6750 RPM. Since the new build's dyno graph reads 132.5 at 6750 RPM, this says that the scaling factor to convert from this particular Dyno Dynamics to that particular Dynojet is approximately (150.2 ÷ 132.5 = 1.134 a. k. a. 13.4% ) Thus the new torque peak of 134.6 ft/lbs @ 7000 rpm translates to a Dynojet number of 152.5 ft/lbs @ 7000 rpm. 

The Result

This result is nicely reassuring since the scaling factor is nicely within both my Tuner's claims range and the range of what you find on the internet. Overlaying the new chart on the old chart, lining up the axes and scaling things to match the above 13.4% factor gets me a comparison chart like this:

Factored comparison of dynamometer results. Note that MPH marked at RPM are only valid for a 4.8 final drive setup. The stock final drive is 4.5, so the 61mph top on the stock trace is more like 67mph in a stock vehicle. Thus I pack this power into a 7% smaller MPH range to begin with.

So the theory of this build was that the top end would gain power and revs, and the bottom end would experience competing effects with CR changes having positive effects and cam changes having negative effects. The hope was that these two would offset each other and lead to an overall faster car. 

I'd say it kinda, mostly worked. 

• 0-4000 rpm we lack good data from the prior build but what is there suggests a definite loss, but this loss is only at launch and only poorly designed courses spend significant time under 30mph. It does seem likely that launch bogging will be a difficulty, but that is < 5% of the course...
• 4000-5000 RPM has smoothed out substantially for a small net improvement which is interesting because my scouring the internet for dyno graphs led me to associate that shape with the PPE Engineering exhaust header I'm using. the fact it went away without changing the header is interesting.
• 5000-6200 RPM has lost some oomph, to the tune of about 10 tq. This is sad, and I did notice it when driving. It's hard to say what impact this will have. 37 to 45 mph is a common acceleration range so this is a bit worrisome. I'll be pondering any ways to improve this. Moving down to a stage 2 cam might help since stage 3 tends to be a peak hp cam. 
• 6200-9200 RPM shows gains are strong and clear and on par with expectations. My build lacks an ITB intake and is clearly running out of breath at the very top, but hits a dynojet corrected peak of around 216 whp, and the ITB setups built by DRS post 220 to 225 whp. I had dared to dream that the big bore throttle body and bigger intake might allow me to capture all of that, but that was just dreaming and I know it. I suspect I did get ~10 hp out of that switch in any case since the hp peak is still around 8k and the compression alone can only account for 205 of the 216 (dynojet) hp. The fall off is faster however so I wonder if the rising intake velocity isn't compressing the foam filter or something. The intake is sold for 400hp supercharged cars but something is up... since the torque peak moved but the hp peak didn't.

So the net result is that my car has become a bit more course dependent, where faster courses should be much better, and slow stuff hurts slightly more. At the end of 2019 I drove 2 courses where I was riding the (then 61mph) rev limiter for 8-10 seconds on a 50 second course, raising the limiter alone is likely worth a half to a full second on such courses, and the power gains in the upper range hopefully worth .25 or .5 on faster courses. I'm hoping I only gave up a tenth or so on launch and no more than 1-2 tenths in the mid range. The only two courses I managed to run in 2020 were both pretty much a worst case scenario with very little time over 50mph (same course designer). I look forward to some faster courses in 2021 to get a real look at what it can do. 

The positive side of that is that most national level courses are faster courses... so it will be at its best where it counts the most. 

So now it's time for you to shoot holes in my assumptions in the comments section if you can :)

The season that Never was: June-Sept

As June rolled around plans to re-start racing were afoot, but soon so was a second surge in COVID-19, and a lot of uncertainty. For most of June and early July I basically ignored my build. My life has me with just 1 degree of separation from some 95 and 100 year old people, and in contact with others that have reason to believe COVID-19 would be particularly hard for. So even if some folks were racing, I couldn't in good conscience go hang out with 50+ other people. 

By August things seemed to have remained stable at a low level in Massachusetts with just a few hundred cases state wide for a while. Additionally several races had been held by several clubs without any of them making the national news cycle as super-spreader events. Thus I began to have some hope that racing could be done safely. I started to work towards getting things put back together. Back in April, I had had a mix-up with ordering heater hoses, and that had to be resolved, which since it involves a lotus parts order took several weeks. Also I had to figure out how to get the harmonic balancer installed. This was complicated somewhat by the extra gear pasted on the front of it to drive the new oil pump. 

The fitment was just a little too tight for me to feel comfortable pushing it on by hand, even though that was supposedly how it was supposed to go. For whatever reason it felt sticky and I *just know* that if I pushed it I'd probably give it uneven pressure and cause it to dig in and gall things up. It was one of those cases where I had that all too familiar feeling that I was about to ignore my instincts and then immediately regret it (much like that feeling when the torque wrench isn't beeping, but the nut feels like its going to strip... and you trust the wrench only to later realize it was set to ft. lbs not Nm... yeah...). So I took a deep breath and... stopped before I screwed it up. 

Of course, the crank has a M12 1.25 mm fine threaded bolt, which is a size that exists in exactly NONE of the harmonic balancer installation tool kits out there. In the end I made my own ordering threaded rod, nuts, washers and a bearing from McMaster Car

Clearly not a solution for tight spaces, but when the engine is dangling from a crane, it works just fine. With this and a just a fine skimmer of light oil, it went right on with no fuss. Then I discovered the bolt that had been sent with it was 8.8... and factory torque says 120Nm... nope. So order a better bolt from Belmetric. 

And somewhere along the line the aluminum underdrive pulley for the alternator had gotten dinged, and had to be replaced... but the alternator nut and hex drive shaft proved a challenge. I wound up ordering a Schwaben 22mm offset open end wrench allegedly specifically designed for alternator nuts. Simple, right? A wrench is a wrench, right? But when it arrived it didn't actually fit! It was 22mm per my calipers, the nut was 22mm per the same calipers, but the corners in the wrench were slightly too rounded... Really Schwaben? you only had one job to do here... only one thing to get right that actually mattered.... (No link for you!)  So since I'd been going through a parade of deliveries, loosing 1-4 days each time I took a file to it and "Made it fit damnit!"... and that worked just fine as, if only as a 6 point rather than 12 point. 

 

So at that point my heater hose finally arrived, and suddenly there was nothing blocking any re-assembly of the front of the car, and also I installed the new Stack Oil pressure gauge, and unblocked the re-assembly of the interior... The number of pieces of my car in the garage was now back ahead of the number in my basement!

Visible Progress! In the forward direction no less!... but then... I found a reason to take the intake manifold off the engine...  That's the subject of the next post... 

The Season that Never Was: Feb - May

In addition to its other more horrific effects, the pandemic also makes for really boring racing blogs. This year was originally supposed to be THE year. as in THE YEAR.... I finally went all in, got the built motor I've wanted for this car since about 2012 .... 

• Brand new OEM block (finally ditching the one my former mechanic nearly destroyed)
• 14:1 Cosworth pistons
• Carillo rods
• Custom DRS spec Supertech valves
• Supertech springs
• Supertech Ti Retainers
• Micropolished timing gears
• ARP head/main bolts
• Daily Engineering external wet sump oil pump
• Ferrea roller rockers
• Piper Stage 3 cams (retained from previous)
• built by Dynamic Racing Solutions a shop with a strong history of successful high RPM normally aspirated 2zz race motors.

This should be sufficient to allow my car to run at 9200 rpm safely, restoring (and slightly enhancing) the top speed in 2nd gear which had been lost with the move to a 4.8 final drive.

It arrived in early February, seemingly with enough time to swap it in and get it tuned. By Mid-March it was clear that the realities of the world at large were going to completely prevent racing for the near term. All events were canceled until further notice. This was a real downer, and I found myself unmotivated to continue for a while. By May things were still in a state shown in this video my wife shot:

Things in progress at the time were:  

1. Swap in full race motor built by DRS Motorsport
2. Refresh as many coolant hoses as possible, including heater hoses
3. Remove evaporator, dryer etc remnants of AC system
4. Upgrade to all aluminum radiator
5. Refresh the steering rack. (it had developed some clunking, usually a symptom of nylon bushings wearing out.
6. Add Oil Pressure gauge

I've started making progress again, so in the next post I'll bring things up to date with the current state of affairs.

New Heights, and New DIY

Once again, I've been slacking on the blogging, but as you will see on the standings page, the season has been progressing, and I've got a co-driver who's giving me some solid competition. The first few events were Freezing, Soaked and Soaked, so I pretty much lacked anything inspiring to blog about anyway. I went to the new Jersy Pro Solo, and had not really found my stride after missing most of 2017 in my car and getting almost nothing but rain events in the early season. I just wasn't getting slip angle like I should, and I was quite dirty, hitting cones or red-lighting on many of my runs as well. As will happen at the national level, if you aren't in top form you're at the bottom of the standings...

Some how I didn't feel eager to write about that either...

However, the weather improved, and satisfactory driving has finally come to pass. I've now managed to regain my prior level of driving from 2016, and in event #5, I finally found a new high point. One of the tough things about evaluating one's performance in autocross is that all measures are relative and the reference point is constantly in motion. To make a sane evaluation one has to make some assumptions. My first assumption is that the top drivers in our region are not getting slower. Given our region's consistent 6-7 national champions the last 3 years this seems reasonable.

While I'm comfortable saying that the top of the heap is still at a high altitude, there are some other things that clearly have changed. Firstly our region has had a buble of talented drivers mature in the last 2 years. I'd not want to argue that any of them have really pushed the top of the pax standings up yet in the way that Billy Davis did in 2015 and 2017, but they have definitely crowded the top. In 2016 I had 3 events where I was 1.5s off top pax, which resulted in 15th, 10th and 15th in overall pax. This year at the last 2 events, 1.5s from top pax is worth 20th and 19th... So making the top 10 or top 20 is significantly harder than it was 2 years ago.

Secondly, pax for the SSM class has been hit harder than any others besides AM, BM and CSP. BM/CSP and SSM are all almost a full percentage point harder than 2016 relative to the other classes. This translates into about .44 seconds tougher pax on a 60 second (raw) course. I've made a spread sheet here that shows that while all pax factors (other than AM) went down, the average pax factor went down much slower for SSM. This probably has something to do with the last 3 champions Thorne, Glagola and Wilcox all hanging out in the top of pax at far too many national events...

With that in mind, the 20th in pax result that had me 1.5 seconds off of top pax in event 5 Looks a lot like what used to get a top 10 in 2016. And my 2.3 seconds off of top pax in event 6 looks a lot like a top 20 in 2016 even though it now shows as 30th. Kudos to my co-driver Daryl, who kept the car in the top 20 at event 6 with his 19th in pax. For 2 events running my car has been 2nd fastest car with doors. Here's a video of my 2nd fastest run from event 5, which is probably faster everywhere except the start where I forget to shift like an idiot... Sadly I didn't remember to turn on the camera for the fastest run.

Additionally, I've also done some more maintenance/improvement on the car. Another factor in my bad results at the New Jersey Pro solo was epic levels of wheel hop on my launches on day 2 when the rubber was creating a lot more traction. A lot of exhaust bounce had also been noted at Devens, and the result was too much for my front motor mount to take.

The alignment was checked and it was almost 6mm toe in, probably due to bushing migration. Soft bushings, lots of toe-in and enormous race tires are a recipe for massive wheel hop. There was only one conclusion, tired old plastic/rubber A-arm bushings had to go. I replaced them with Monoball metal/teflon spherical bearings from Inokinetic. Since this seemed like an interesting job, I also made a DIY video for it:

The results? FABULOUS. Both me and my co-driver Daryl noticed improvement in the predictability of the back end when rotating it around a corner, and improvement in braking. The first was expected and the second was a nice surprise. My rear suspension had probably become so floppy that the ABS probably triggered earlier. I also suspect this slop negated all rear braking once it triggered by wagging the A-arms back and forth with the ABS pulses. The start for this course did not lend itself to hard launches, and due to the late date of it's discovery I had to continue with the above mount after Ryan welded the split for me. Next event we will be doing full launches if the course allows it and then I expect to find that the wheel hop has also improved.

Return of the SoLoti

So yeah I got tired of blogging about how my car wasn't working... probably you got tired of hearing about it. Then when I finally got it working in September I spent all available weekend time driving it rather than blogging about it. I had a little bit of pent up racing to let out! Then I took on a new client and have had 1.25 people's worth of work to do...

So what's the story? Well, After waiting forever and then some for a valve tool to arrive at the shop that did the install of the head that was supposed to make it easier for him to check on the valve seals, I lost patience and took the car to MC racing, and they hooked up a compression tester and a leak tester, and whoosh... air in one piston and out the other... Clearly the head gasket was not sealing properly. Perfect proof that it is so very good that Nick my tuner at Ace Performance refused to tune with the car as I delivered it the first time. Kudos to them!

With this new information I contacted the original shop and they started pointing out that I supplied the head gasket etc... basically preparing excuses to not make it right. That sucked but there is of course enough gray area for them to avoid the work if they so chose. Fighting over it was clearly not a productive route to go, so I took it back to MC racing and for 2/3 the cost of the previous shop they took it apart, machined it, provided a head gasket and re-assembled it in working order. There's still a slight bit of smokiness, but nothing like before, and unlike before, when things warm up the smoke goes away. I suspect some things are not quite perfect due to the previous install, but now it's close enough that the thermal expansion completes the seal as the engine warms up. I'll be analyzing oil and keeping an eye on it going forward. If I ever go to high compression pistons, it won't be on this block/head combo.

Speaking of oil, I've moved to red-line 40wt race oil now that the car is a full time trailer queen and never does more than idle around before it's fully warm. In theory this allows a slight hp gain and better flow when warm, at the cost of a little more flow resistance (and thus wear) during startup. It's also the case that with a trailer queen, it is a lot harder to just bop on over to get an oil change, so I'll be moving to changing my own oil and brake fluid. To make that easier, and to help combat the flow resistance at low temp, I went to a Canton Racing  spin on oil filter which gives me about 3 times as much flow as the stock filter and 8 micron filtration.

I know what you are probably thinking... the man dumps umpteen zillion dollars into head work, ecu and tuning and he's blogging about his oil filter?? Point taken...  I'll get to the good stuff now.

So with it back together and (mostly) not smoking, tuning was possible, and the results are very pleasing indeed!

I never had a chance to get a baseline, so the above plot shows the results vs a stock plot I grabbed from the web and scaled to match. These numbers are a couple HP better than any other normally aspirated plot/numbers I've been able to find for cars running stock compression. And these are with the super trap on! Based on a single test run, there's perhaps another 2 hp in it if the super trap is removed. I only have good things to say about Nick's tuning, and Baer who runs Ace Performance was straightforward and easy to work with. I'm very happy to be promoting them on my wing plates!

The Emtron Ecu installed by Ace Performance has all kinds of super nifty logging and capability. No end of parameters to ponder! Below you can see the data, possibly even from the above photo. The slalom in the photo would correspond to somewhere around the 6000 second mark below, but I cant' be sure if it's exactly that run or not.

And I also got a beta version of CAN bus support for the stock dash, which so far seems to work great! Nick/Ace/Emtron will be coming out with new info on their products soon and when I'm allowed to share some stuff I've seen previews of, I'll post it here. Until then, we'll all just have to visit the garage, glance out the window at the snow and sigh... And comb through data logs :)

...Gang aft agley!

The start of this season hasn't gone as I had envisioned it. The vision in my head mid February went something like this:

• Head swap mid-March
• Tuning late march/early April
• Learn the changes to car at Event 1 and in the next Renegade event. 
• Race #2 expect decent result
• more practice events
• Race #3 and onward... full speed ahead, chasing another top-10 & class wins to try try for a second season championship, with Leafy doing his best to make it tough (cue the stirring music, with videos of wobbling cones, and spin outs and times in red LED letters, people cheering, other people shaking their head or pounding the wheel... etc...).

It sounded like a nice plan, but like most plans, the intersection with reality was disruptive. Actual results were more like:

• Mid-march - Mechanic no space to work on car, must wait.
• Late march - Delivered car to mechanic
• Early April - Headwork more involved than expected due to one unreachable bolt, timing chain cover comes off to detach timing chain guide from head.
• Prep for race 1: Drove other folks cars at test and tune (thanks Bill, Thanks Jake!)
• Race 1: Co-driver lends me his car (Honda s2000 in full STR prep) wind up in 4th place, Co-Driver takes 1st with a time that (if STR pax) would be 7th in pax.
• Cancel reg for NCR Porsche, miss Renegade event
• Mid-April Mechanic reports head on, difficulty shimming the valves, some are too tight for shims
• Race 2: Co-driver again lends me his car, take 3rd place, with co-driver again taking 1st.
• Late April - difficulty getting shims.
• Early May - one valve so tight, even 00 shim won't work, contemplate head off and shave valve stem.
• Mid May - Consultation with machinist leads to shaving the shims instead of the valves
• Miss 2nd Renegade event...
• Event #3 - Co-driver at wedding, Drive Matt's ASP prep STI - take second place
• Late May - Car Runs! Get the car back, 
• Tuners, no space for car, must wait.
• Tuners schedule me for tuning in very early June.
• Miss 3rd Renegade event, Cancel Track Club Event... 
• new ECU installed and starting

So, If I'm very lucky I'll get two events worth of practice before the national tour, maybe 20 runs to settle into the new setup, and if any minor delays, only one event... if a major delay... I miss the tour, which counts as events #4 and #5.  Sadly (but lucky for me points-wise) Leafy also has had a slow start to the season and his car will also make it's first appearance in the tour. Where both of us will have to contend with Todd Kean (alien) in the #99 Nissan S240 "Panda" (space ship).

As for season points... well, the good news is Leafy mostly drove cars even less SSM than I did, and I'm well ahead of him. The bad news is Nick, my Co-driver is scaring the crap out of me by posting crazy good times in his car. I certainly expect a little bit of a break when we switch to my car, due to home-car advantage, but I'm thinking once he adjusts, he's going to be pushing me pretty hard (which is good!)... 

Nick's skill only adds to the fun of course. This year SSM seems to also have SML national champ in the Kuehl's SMF CRX... running in SSM for fun... sure it's SMF, but it's possibly the fastest SMF car in the nation, and she's a national champion. Next event, we get to see the long awaited result of Leafy's motor swap. He put a 2.5L engine in his NA Miata and turbo'd it... probably for 400+hp! This year, there is competition!  

On the plus side, I did get to drive some interesting cars. Many thanks to the owners. Here are some pictures of the cars (only the S2000 is a picture of me driving though with Nick passenger):

Updated:

• Tuner refuses car for Tailpipe smoke issue... ARGHHH!
• Drive Derek's S2000 at BMW
• Drive Nick's S2000 at Porsche Club and National Tour
• Still waiting for the music...

Thanks Bill!

Thanks Jake!

 Thanks Nick!

 Thanks Matt!

PS. if you don't get the title of the post, it comes from a rather famous poem called "To a Mouse" by Robert Burns... the full line is:

The best laid schemes o’ Mice an’ Men 

          Gang aft agley, 

Looking forward to 2017...

ARP head bolts...

JCR Fab Ported Head

Piper Stage 3 Cams

Mechanical work complete - next: Tuning!

Ready for 2016

Changed (+17lbs):

• Front: 275/35/15 on 10.5" wheels from 205/45/16 on 6.5" wheels
• Rear: 275/35/17 on 10.5" wheels from 245/45/17 on 7.5" wheels
• 800 lb/inch rear springs from 650 lb/inch
• 8mm higher rear height to prevent spring rattle (need tenders)
• Stiffer front sway bar setting to compensate for spring change

Maintained:

• Front pads/rotors

Removed (-9lbs):

• Mudflaps, 
• Front fender liners, 
• Fiberglass around wheel well to prevent rub.
• Wheel spacers
• Side verticals on splitter (comply with new rules)

Photos:

Like LSD man...

Ok sorry for the goofy title, I couldn't resist. So after doing all the work of pulling out the transmission, it became very clear that I want to minimize the number of times I do this. It's sort of fun in a way, but it really does take a lot of time and effort. So besides replacing the tattered, clutch that was probably a hairs breadth from grendading like this one:

The flywheel, and the Limited Slip Differential (LSD) were also installed. Basically, as a consultant, my time can be converted to money fairly readily and long term it's cheaper to do it all at once.

The flywheel is the Fidanza Aluminum flywheel, which shaves 6.8lbs off (about 45%) the stock. The clutch plate itself is only an ounce or two lighter, but it has less mass near the edges, and the clutch plate cover and pressure plate is a pound less, so the total weight savings should be about 8lbs of rotational weight. 

The LSD will offset that somewhat, adding back a couple pounds or so, but the diameter of the added rotational parts will be small, so perhaps 5-6 lbs off the car, and even more reduction in rotational inertia. PLUS power will now be available in the corners!

Only one problem... with great power comes great responsibility. It turns out that a lot of the time I've not been very gentle with the throttle. The LSD exposes this flaw in my driving in 2 ways. First, if lateral grip is not at maximum, but the car is turning, when the LSD locks up, this results in power only on the outside wheel (since the axel has become solid the inside wheel with less weight and traveling a different radius must slip). That tends to torque steer the car into the turn. This is potentially useful, but also throws you off if you are not used to it. Second, if you are at the limit of lateral grip, adding power now causes the OUTSIDE rear wheel to slip... and that will tend to make the car want to spin.

So while the LSD unlocks a new level of potential speed, the open diff will tend to save you from yourself, and is slightly easier to drive. My first event on the new LSD was quite disappointing because I was discovering that my throttle work needed work. After about 5 events, now I'm getting used to it and learning to ease onto the throttle and not be on/off the throttle as violently, and may just be beginning to reap the benefits of the additional speed in the corners.

Other notes on the changes I made... the lighter flywheel seems to make it slightly harder to get the car to actually turn over, which puts my present battery solution right on the very hairy edge... I probably need to think about setting up a cold weather jump system to ease the wear and tear on my starter when I have to leave for a race in the early AM. Mostly I just need an easy way to get jumper pack clamps on the battery.... without risking a short. The present space is pretty tight.

Waiting for the thaw...

Such a winter... 3-4 ft snow in the yard at max. Many all time snowfall records broken, season record in jeopardy. Even more amazing, it went from almost zero to nearly a season record in under a month. Not much was happening in early winter, so I didn't bother trying to manufacture a post. Then later, I was preoccupied with climbing on my roof to hack off the ice that was almost a foot thick in places...

With winter wrapping up and warm weather on the horizon, of course the car is somewhat disassembled... So I don't have time to write anything interesting now either, but I can offer you some pictures of lotus guts...

So obviously, the clutch is getting replaced.... other mods TBD, time/$ permitting...

Stay Cool FTW

When one gets a run of continual improvement going it has a sort of magic of it's own. Each time out there is the dual hope that it will continue, and fear that the bubble will burst, and the streak will be broken. I have a streak of improvements with each event this year, and as a result I am already bursting through my wildest expectations at the beginning of the year.

Two events ago, I went into the event, more or less having achieved my goals for the year, with several events putting me in the top 20-25% already. Then I ran 22nd of 139, just one place (and 0.091s) short of my top 15% stretch goal. It was fabulous, but how on earth could I top that? How do I keep the streak going?

Well, my tires were mostly toast, ending the last event at 120 runs and 138 after the last renegade event. The 70 run tires I took off just before the tour went back on. Changing setup and car balance during the season can be disastrous, if the car behaves different and you can't adapt, cones and slow times will often result. But, I was facing elimination in the points race. If I lost, I would be mathematically eliminated and the final event of the year would amount to a test and tune/fun runs. With this in mind, I decided to fix the front splitter.

Over the course of the season, the plywood splitter I had added had become warped. Attached at the front and the back with foam to seal the air in the middle, it the middle was bowing downward, and the car had started to push. Both Ben and Brian remarked on it, and I felt it too.

This warping is a result of my insistence on not attaching the splitter to the fiberglass. Attaching to the frame in the back with supports on the front was fine when I was using a carbon fiber splitter, but not so fine with plywood, especially after it got wet.  I needed a stiffener. I didn't want to add more aluminum angle along the bottom. The front already scrapes on the occasional curb cut if I'm not ultra careful about where I drive. Adding something that hangs down further would not work, and of course I always want to minimize the weight. Thin, light and stiff made me think Carbon Fiber. I found some economy 5mm 6"x30"  carbon fiber for under $100. 5mm CF is rock solid. When I got it I could barely flex it at all. So I applied that along the top, eliminating the aluminum bar that hung down in the middle previously

I probably gained a few ounces, but I only have the "feel" of it since I forgot to actually weigh it. In any event it worked marvelously...

Much straighter, much tighter to the bottom of the car. But would it mess up my driving, or help it?

SCCA points Event #8 was a cool, blustery day to start, Morning runs for the 3rd run group were in the low to mid 60's. My first run was messy and slow. On my second run I spun in a slalom, but I got a good practice run at the finish. Both Dan and I noted that the car felt different and that the push was reduced, or maybe gone. Sounds like a disaster in the making...

BUT here's where the seat time this year paid off. I didn't panic. Instead I set about trying to figure out how to adjust my driving. I said to myself... "If it's not pushing at high speed anymore, that means I should be able to nail the sweeper hard. I need to set that element up so I can take advantage" and I also said to myself, "I need to be extra careful on my entries to the slaloms...." My 3rd run of the morning was faster and clean... and came in just 0.4 sec behind Leafy, whom I needed to beat to remain in the hunt for a season championship.

While I was fairly happy with the first part of my 3rd run, I knew that the finish had been a near disaster. I had become late on the angled walloms, and then been forced to focus on controlling the car rather than putting power down at the finish. I only just barely touched the rev limiter at the finish line. When I checked the numbers, my run was fairly decent. After the rest of the morning runs finished. I was 2.8 seconds off top pax, which usually equates to a top 30 finish. But of course folks will find time in the afternoon, so I need to find time as well. I said to my co-driver Dan, "I need to put the finish of my 2nd run on the first 3/4 of my 3rd run."

Then came the afternoon runs... Temps were up by about 5-10 degrees. The tire blankets were not needed, but it was still cool with somewhat less wind. On my first run, I more or less did what I set out to do. I pasted together the front of run 3 with the end of run 2, and managed to find half a second, enough to put me in the lead vs Leafy's morning time. But I knew that Leafy would likely find time too. Reviewing the run in my head, I decided that I still wasn't working the first part of the course hard enough.

On my second run of the afternoon I found another .8 seconds which firmly cemented my lead, but I FORGOT to turn on video! DOH!! However SoloStorm did start it's data logging, so here's a video of my 3rd run of the afternoon which was as fast or faster than my fastest until I botched the finish (if you ignore the cone). Overlayed on that video is a video of the solostorm comparison playback with my fast run (run 5). The paragraph that follows is my from memory description of run 5 (not 6 which you see in the video)

So here's my "in-head video" of run 5, (the green line on the above video):

I made a more agressive start and it felt good but I slightly under broke in the turn before the big sweeper, so my sweeper was a tad slow, however I kept my foot in and built good speed, barely taping the breaks to get through the following slalom. As I did so, I realized I probably didn't even need to touch the brakes, and I felt I slightly over broke on the turn towards the taxiway too. As those thought flitted by, I immediately said to myself, well if I'm a little slow, I should be able to get a good turn onto the taxiway to compensate. I remember feeling that I did a good job of the turn, but didn't really get on the gas until the end of the taxiway. The surge of power as the cams kicked in at the end of the taxiway reminded me of some other times I had overshot breaking points, so I laid into the breaks as hard as I could, and then let off and just turned the wheel where I needed to and prayed it stuck. It did stick, but just barely. The back end slid just a tad and then hooked back up, putting me in a pretty good position entering the main runway. Even as I was noticing this, I found myself thinking "GREAT, lets take advantage of this!" and I accelerated out of the turn as hard as I could. This actually put me just slightly shallow on my entry to the first slalom on the runway, but I realized I was not getting a great entry and with a quick stab to the breaks managed to rotate the car and get in half way decently anyway. I knew I was immediately facing a cut back across the runway at the end of the slalom, so I only fed minimal throttle to avoid making that turn too difficult. This worked well, and I got a more comfortable entry into the second slalom. With a good position on the second slalom I was able to be on the accelerator at the cone before the end of the slalom and gained a lot of speed through the slanted six pack. Much like the exit from the taxiway, this left me slightly shallow and I again compensated with a stab of the breaks. Then through the walloms I worked on being patient and getting ahead of the cones in preparation for the finish. I was able to mash on the accelerator and I knew I was going to be all over the rev limiter so I tried to go to third and missed (oops).  As I crossed the line, I wasn't quite sure how I had done, it felt clean and fast, but I'd been so busy thinking and adjusting through the run I wasn't sure. When the display read 50.9 I was shocked and elated, and prayed it was clean, which it was.

In retrospect this run was a huge achievement, but not because of the time or the PAX position. It was huge because I had retained focus, and adjusted on the fly effectively. In essence, I had successfully implemented the advice Eric Chiang had given me a year and a half ago. I drove the car as it was on course. I drove based on the feedback the car was sending through the steering and the seat of my pants and by the status that my looking ahead was giving me. A year and a half ago I was falling prey to driving based based on my expectation of the course. Eric had noticed when he road with me that I accelerated in some spots beyond what made sense, and guessed correctly that I had been thinking to myself  "I should be fast here, I should get to the rev-limiter." He said it was a common problem and hard for some people to overcome.

I also felt that the run was a huge achievement in that I went from coning and spinning in a car that was doing new, strange things to running my best time ever within a few runs. Even better, it's easy to see from the above video that there was more time out there 50.4 seems very doable, and that would have been top 10 (just barely)!

Here's my thought on all of this... the big thing that seat time gets you is a familiarity with driving at speed. It brings instant recognition of "Oh crap, I'm getting too fast, brake hard NOW!" (e.g. at the end of the taxiway), and the calm analytical workaround of stabbing the brake to help rotate the car on a less than ideal entry. It allows thoughts about where to go faster next time without becoming disappointed or distracted, and it allows you to find the silver lining when you are slightly slow and just keep driving... I finished that run, my fastest ever, and I didn't have the shakes, I wasn't out of breath. I had remained calm and focused throughout, and that's probably why it was possible. Without that calm, the success of the hard breaking would be wasted on relief that I escaped disaster. Without that calm, the timing of the break stab would likely be early or late doing little good at all.

And as I said in my last post... drive fast, and the points will follow. I won first place and I remain alive (if just barely) in my hunt for a season championship. I think my driving at this event this event was championship level driving, but alas, I was not driving like a champ at the beginning of the year. I have to hope that someone beats Leafy, and I beat them. With a result like today, where I was almost a second ahead, it seems like a possibility, but very very far from a certainty. I'll give it my best, but smarter money is on next year at this point.

I really hope I can keep my cool like that in future runs. The results are waaaay cool :).

New Rotors, New Acheivements

Autocross eats brakes. It's just a fact of life. Tires too. My wife still marvels at the idea that I replace race tires after 100-150 miles (while most racers marvel that I wait that long!). Brakes are somewhat better, the Sector 111 Ultra disc rotors I have been using lasted about 2 years in the front and 3 in the back. That doesn't sound too bad until you consider that I put less than 5000 miles on those rotors. Guess what... after the last event, my front pads were getting very thin, and I was seeing bluing from heat where the vents in the rotors were. It was kinda neat, almost like an x-ray of the rotors, but what it really means is that the rotors are too thin, and not discharging the heat well anymore.

The Ultra discs and super grippy Porterfield pads were a marvelous improvement over stock, but every now and then, it seemed like the brakes just didn't quite do what I expected. With this combination of pads and rotors I had begun to suspect that while it gives you most of the power of a big brake kit without the weight and price penalty, they still lack something in terms of modulation. To try to improve the situation, I decided to try the new vented, slotted, full-floating rotor offered by Beyond Original Equiptment since they claimed to have better breaking modulation for a similar price. I left the Ultra discs on the rear because they are lighter, and also because the fronts do the lion's share of the work.

I ordered the rotors immediately after my last races and they arrived in about 3 days. There was a small issue I ran into, but BOE has EXCELLENT customer service, and they resolved it quickly and professionally. BOE has become a leader in aftermarket lotus race parts, and you can definitely order from them with confidence. There's a bunch of pictures of the rotors on their web site, but none after the black coating has worn off, so here's what they will look like after they've seen some wear.

Looks are nice, but this is a race car, not a concourse car. What matters is results! The first event was Renegade Miata Club's 5th points event of the year. This event was opposite the SCCA's Racing against Leukemia charity event, and so I expected a soft turnout. The attendance numbers were somewhat low but luckily, the top of the field was still pretty typical. Bob Lang And Leafy didn't show, but Lanna and Hank, who are both national champs did. Scruffy didn't show but Grant and Steph were there, Mike Stukalin was there an he's always fast. Furthermore the New England area seems to have acquired a new hot-shoe, Ryan Field who was there in his CSP Miata. So the competition could even be considered slightly stiffer than normal.

My result? 5th raw time... again. Not exciting on the surface but if you dig into the numbers a bit, to retain the 5th spot I had to drive faster than Matt Mickle, which I have not previously done. I was still 1.25 seconds behind grant though. The pax factor vs Grant however is 0.958. That is way better than I usually do at NER SCCA autocross events. However, this year Grant has not been dominant as in past years, so perhaps an NER pax factor could be as much as 0.015 tougher... or maybe not? Hard to know I was just as close to him at the Match Tour. Even so, it would still could be my best result ever. The other good news is that even if they were running crappy old tires, I was too. My tires ended the day on their 99th run. The great thing about new tires, is you go faster than old tires. The great thing about old tires is if you do well when you are on old heat cycled tires, that means you simply drove better, or did something good to your setup.

Event #1 on new rotors: Success!

So the second event was Points event #7 for the SCCA season, and as I said before, this is where it counts. At the start of the race I was 6 points back in the standings (after accounting for drops). I desperately need a win to stay alive. On my first run I put down the fastest time of anyone's first run in the first session. On my second run I shaved another 4 tenths off. That doesn't sound that impressive, but this event was in the small parking lot at NHMS, so my times were 28.8 and 28.4 respectively, and this was equivalent to finding almost a second on a Renegade course, or .8 seconds on a course at Devens. As I returned from that run, they announced I had Top Raw time and Top Pax! Now THAT has never happened before. It didn't last, Billy Davis took it away on his next run, but it sure was a fun thing to hear. In the afternoon I ran a 28.3 and another 28.4 shaving a small amount but not really improving much. I was a little disappointed that I didn't find a 27.x but I had multiple people tell me how good I looked out there, including some really good drivers. These sorts of compliments seem to be happening more often lately, and I'm not getting the highly dubious "awesome spin dude" or "that was awesome when you drifted through that corner" compliments from the novices as often.

And the points race? After the morning session I was ahead of Leafy by a good margin, but the same thing was true last year, and then he found a ton of time in the afternoon and beat me, so I was very nervous. I may have begun over-driving on my last runs for fear he would catch me again. Sure enough he found lots of time on his first run of the afternoon, running a 28.2 but he also had 2 cones. On his second to last run, he was clean.... BUT he was still 0.2 seconds behind me, and he coned his last run. I finally picked up a class win and now sit in second place 3 points out of first. If I win next weekend I Tie things up with one more race to go. Also, I was 14th in pax of 57 or so competitors, which doesn't look that great until you consider that most of the folks who don't come to the New Hampshire event are the novices and casual folks and the people who do show up tend to be more skilled and involved in tight points races. For this reason I long ago stopped using these events in my stats calculations. However, with Billy Davis there, top Pax will not change much vs a regular NER event and my PAX factor for this race was a nice leap forward. I scored 0.949 vs my previous best of 0.938. I was 1.2 seconds off top pax which is approximately equivalent to 2.4 seconds off top pax at Devens... also a nice step forward. So all crazy attendance factors aside, I feel confident saying that this was my best race ever.

Event #2 on new rotors: Success!

So is it the Rotors, or the lessons of Evo School finally sinking in? Hard to tell, but one thing can be said for sure, these rotors have shown a positive correlation with successful autocross! Next weekend is another SCCA race, this time at Devens... The full long course. Many folks there will be gearing up for nationals. If I can do well at that one, I can do well almost anywhere.

Video with Data!

Yesterday was the Renegade Miata Club's School event which is a great opportunity to test out the car, and my new data/video equpment while getting advice from top drivers in the area. The day was a distinctly New England day... it started dry/cool, moved to wet, cold and sleeting and then the sun came out dried everything up and temps moved up into the 60's. In any case I sorted out some kinks and began to remember what to do when presented with several hundred orange cones, open pavement and a lotus.

Here's a video with data for my second fastest run of the day... 72.6 seconds. I didn't bother to shoot video for fun runs, when I had a 71.1.

The video was shot with a Sony Action Cam, data logged with a Race Capture Pro data logger, and video rendered with Race Render. It all worked great except Race Render doesn't seem to like empty values in the first row of data, so I had to open it as CSV in copy a couple of values from row 2 to row 1 to get it to recognize the columns properly. After that it was a breeze.

I'm very pleased with the quality of data from Race Capture Pro. It has none of the jitter an looks way better in Solo Storm than the MaxQData logger I bought 4 years ago (for more money). Of course in fairness to the MaxQ folks this could be because I actually took the time to mount it on vibration reducing mounts bolted to the dash rather than just slapping on a bit of velcro on it...

Splitting Airs

Last winter I shifted my splitter forward 2 inches to try to get more front down force, but it seemed to have a very limited effect. This is probably because the main protrusion of that splitter is just in front of the radiator grille. The air flow in the radiator and up over the car is not very significantly restricted, and less so with the AC condenser removed. Thus, the increase in pressure over the splitter vs under is probably minimal there. The sides gained extension too, but the sloped, drag reducing front of the car is probably also fighting the build up of pressure as well.

Since I improved the wing over the winter, I expect to generate more downforce in the back. To make use of that added downforce I will need more front down force. Otherwise I will simply go back to the car plowing on the fast sweepers. To that end, I've ditched the CF splitter and cut myself a much larger plywood one, similar to that used by the other street modified cars in my area. Here are some pictures of the construction process....

Jack it up, prop the board underneath

Scribe a 5.75" offset from the fender (viewed from above). The rule is 6", but leave a bit for safety and interpretation etc.

Painting with Rustoleum to give it a little water resistance...

Initial attachment.  The sides still need trimming, they stick out a little bit too far.

View of bottom attachments. As always I am attaching to hard points, not the fiberglass clam

If air passes above and below an added aero dynamic aid it is considered a wing. Front mounted wings are disallowed in the super street modified class, so trim the ends and put a back plate in to turn it back into a splitter

Another view. It's hard to see because of the paint, but Aluminum angle is used to attach the backplate

The final result from the front

The edges ere a bit floppy and I didn't want to attach to the fiberglass, so I rigged a turnbuckle system attached to the oil-cooler mounting point which is steel.

A slit in the fender liner is required. Re-installation is quite a trick since the top part of the fender liner is actually supposed to slip in first, but that is no longer possible. Really glad that i was conservative on the size of the back plates.

Ever so conveniently the vent for the oil cooler accommodates the turnbuckle! 

The result is that the turnbuckle system is not 100% rigid, so I may need to re-work this if the edges wind up flapping, but it should also work to dissipate and absorb some of the energy from cone impacts. The great thing about this is it was really really easy to install and provides a bit of adjustability if the corners turn out to be pulled upward by the tension (which is not legal if it's more than 3 degrees from level)